Pipe bending machines of this type and rotating bending heads adapted to said machines have been described, for example, in French Patent Application No. 2 610 852, or in European Patent Application No. 0 281 488 in the name of the Applicant.
In such known bending machines, the two bending heads are normally placed on either side of a fixed or rotating central clamp designed to hold the pipe to be bent. During the bending process, the two bending heads, operating simultaneously or alternatingly, are moved progressively towards the central clamp, each bending head allowing several successive bends to be made in the corresponding half of the pipe, and the different bends possibly being located in different planes from each other. It is understood that bending machines of this type allow multiple bends to be made efficiently in relatively long pipes, and, accordingly, said machines have applications primarily in the automobile industry, for example, for making brake system conduits.
Nonetheless, said pipe bending machines still present problems that limit their possibilities for use. In particular, it is still difficult if not impossible to make closely-spaced bends in a median area of the pipe because the central clamp is usually present. Indeed, said median area is gripped in the central clamp, which is an obstacle that limits the translation movement by which the two bending heads move together. Thus, unless special arrangements are provided, the minimum distance between two bends in the median area of the pipe is equal to at least twice the length of a bending head plus the width of the central clamp.
The mere elimination of said central clamp is not a valid solution to the above problem because the pipe still has to be held when the last bend(s) is (are) made in its median area.